Sabrina's resting heart rate is 80 beats per minute, and her resting stroke volume is 50 mL per beat. What is her cardiac output? When she exercises, her heart rate increases to 100 beats per minute and her stroke volume increases to 55 mL per beat. What happens to her cardiac output? What is the advantage of the lower relative increase in stroke volume?
What will be an ideal response?
CO = HR × SV. CO = 80 beats/min × 50 mL/beat = 4000 mL/min at rest.
During exercise: 100 beats/min × 55 mL/beat = 5500 mL/min.
Overstretching of the heart muscle during venous return could damage it; thus a relatively higher heart rate is a
safer way to increase cardiac output.
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